BACKGROUND:Shadoo is the guard of the Flopside Pit of 100 Trials. It was granted the power to transform into a shadow version of anything. It transforms into Luigi, Bowser, Peach, and Mario (in that order) and attacks Mario and company. It also created dark minions for the pit of Flopside. Eventually, Mario and his friends (and one enemy) destroyed it. Apparently, it guards all the Paper Mario Catch Cards.